[SOLVED] Get the first of many similar strings

Issue

I have strings of the form

A-XXX
A-YYY
B-NNN
A-ZZZ
B-MMM
C-DDD

However, I want to get the first occurrence of every string before the hyphen. So the solution here would be:

A-XXX
B-NNN
C-DDD

How can I do this with bash tools? I tried uniq, but I can't set the "similarity-pattern" there.

Solution

Will this suffice?

cat uwe
A-XXX
A-YYY
B-NNN
A-ZZZ
B-MMM
C-DDD
$ awk -F'-' '!a[$1]{print $0;a[$1]++}' uwe
A-XXX
B-NNN
C-DDD

EDIT:

One can actually shorten that to the slightly more cryptic:

$ awk -F'-' '!a[$1]++' uwe
A-XXX
B-NNN
C-DDD

What we do is to tell awk - is the field separator; !a[$1] tells awk to execute the following commands (with nothing given print is the default), and post increment the array that checks whether a value was seen.

Answered By - tink